I am in the middle of upgrading exterior lighting on the car to LEDs. The car, an 89 IROC, is completely stock and original with original wiring and electronics. So far I have installed JW Speaker headlights in all four positions, Endpage white/amber switchback 1157s as running lights, and Philips T10 side markers up front. I have already replaced both flashers with no loads.

The problem I am seeing up front is the low beam will flicker when just the driving lights are turned on and the high beam will flicker with the low beams on. I tried using one of JW's anti-flicker harnesses made for a Jeep installation with no noticeable change.

Anyone have a solution up front?

 

Solved my issue with tail lights. Looking still for input up front with headlight flash.

 

Following.

 

I have an 89 Firebird with a 100% stock uncut wiring harness . I installed LEDs in all of my exterior lights and have had no problems with flickering or anything odd like that . Naturally I did have to buy the electronic flasher units for my turn signals and 4 way flashers , but this was a simple plug in replacement for the original that has a 3rd wire that needed to be grounded for the electronic circuit in the flasher to work correctly . Rock Auto sells the right flasher to use for around $10 . So I'd say if you have odd flickering issues it's either the LEDs themselves or perhaps somethings not quite right with your car's wiring ? (Arcing connection or something like that ?)

 

I had a flickering issue with my halogens. It was because the headlight pins were not wired with the pins in the socket. In other words the ground in the socket was going to the low beam tab on the lights. Make sure the proper wiring to the new LED's If they are crossed you will get flickering. The other common cause is switch overload. New lights draw more amps from the headlight switch and causes the switch to overheat. I would think LED draws less but I have seen bulbs with cooling fans so those must draw.

 

Thank you to all who chimed in. I think I was able to pull some advice from an older thread about upgrading wiring. Some members were seeing problems with their fog light relay not working because of the extra voltage that runs through the high beam wires, even when the high beams are off. This 5-7 volts seems to run through the green wire that is shared by the high beams and fog lights and uses a relay to shut the fog lights off when high beams are on and vice versa. The problem with the extra voltage is it was high enough under circumstances of upgraded wiring to keep all the lights on once members tried to turn their high beams back off.

One member noted that on some wiring diagrams the high beam bulb was marked "R" as if to denote it acting as a resistor that took this extra voltage out of the line. When I plug one of my old lamps into the high beam harness my flickering in my low beams goes away.

So long story short, how do I address the extra voltage in the high beam line without cutting stuff up or losing functionality? I'm not great with wiring and electronics so don't assume I really understand what adding a resistor or grounding an additional wire are supposed to do.